1. Field of the Invention
The object of the present invention is a container, made of flexible material, and a method of production thereof.
The container according to the invention, in its different embodiments, is particularly suitable for vacuum-packet or non vacuum-packet powder products, and also for containing liquid or powdery products and for sterilizable products.
2. Description of the Related Art
Various types of containers are in existence on the market.
For example, flexible containers are used for conserving products in powder form, such as coffee, under vacuum; these containers do not keep their shape after opening (they collapse), with the obvious drawbacks this entails, or rigid metallic containers are used (for example tins) which, however, tend to be expensive and retain their original bulk after use.
The latter type of container is widely used also for liquids and sterilizable products.
Semi-rigid cardboard containers are also in use for liquid products, such as fruit juices and the like, usually having a layer of aluminum interposed between an outer cardboard and an inner plastic film. These containers have a cost midway between the ones previously described, and although they are sufficiently rigid, they cannot be completely recycled becaused of the non-homogeneous nature of the materials making up the various layers, which is a problem also found usually with the flexible containers first described.
A semi-rigid container of the type just mentioned is described, for example, in Swiss Patent Application Serial No. 385,100, which comprises a bottom lid, a top lid and a skirt presenting an external layer made of cardboard material and an inner layer made of polyethylene. The jointing of the skirt takes place along a vertical strip, by overlapping its two adjacent edges after having removed a cardboard strip on the internal edge, and by heat welding the polyethylene sheets which come in contact. The jointing between the edges and the lids, which are made of plastic material, takes place by inserting the skirt edges into corresponding external peripherical foldings of the lids and by effecting a welding.